Evaluations of special education interventions are different from research on medical interventions. Educational evaluations would be more useful if they applied an actuarial, or probability approach. Information should be collected over time and using various measures, thus increasing the available data. (GDC)

Point of entry problems are faced by evaluators when asked to start an evaluation at an inappropriate time or to perform an inappropriate study. The fundamental purpose of evaluation is to help improve services. Guidelines are presented for choosing when to do a context, input, process, or product evaluation. (GDC)